Performance Modelling of Wormhole Switching in Two-Dimensional Torus with Finite Buffers

Over the recent years, a great deal of effort has been devoted towards the development of analytical models for wormhole-routed networks. However, most of these models employ routers with negligible flit buffers. As a consequence, they do not adequately capture the performance behaviour of actual routers, which are often equipped with extended buffers which can hold more than one message flit. In this paper, an open queueing network model (QNM) is proposed for a wormhole-routed torus with finite buffers subject to a compound Poisson process (CPP) with geometrically distributed batches. The GE/G/1/K queue and appropriate GE-type flow formulae are adopted, as cost-effective building blocks, in the solution process of the entire network. The validity of the model is demonstrated by comparing analytical GE-type results with those obtained through simulation experiments. It is also shown that the wormhole routing based torus network suffer progressively performance degradation with increasing traffic variability.